Goodwill And Other Intangible Assets (Goodwill Assets by Business Segment) (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 501,884
Goodwill Acquired	9,106
Impairment Loss	0
Goodwill Adjustments	(1,033)
Ending balance	509,957
Community banking
Goodwill [Roll Forward]
Beginning balance	429,520
Goodwill Acquired	9,106
Impairment Loss	0
Goodwill Adjustments	0
Ending balance	438,626
Specialty finance
Goodwill [Roll Forward]
Beginning balance	40,250
Goodwill Acquired	0
Impairment Loss	0
Goodwill Adjustments	(1,033)
Ending balance	39,217
Wealth management
Goodwill [Roll Forward]
Beginning balance	32,114
Goodwill Acquired	0
Impairment Loss	0
Goodwill Adjustments	0
Ending balance	$ 32,114